Market Service Tech

Leslie Orm
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Essential Terminology

  • STACKING GAS – Liquid hanging out in the condenser due to low ambient conditions.
  • LOW SIDE PRESSURE – Suction or Back Pressure.
  • HEAD PRESSURE – Discharge Pressure, be it liquid or Vapor. (HI SIDE)
  • COMPRESSION RATIO – Refers to the compressor. To get compression ratio, add 15psi to each value, then divide SUCTION pressure into DISCHARGE pressure. 
  • SDFF – Single Deck Frozen Food. Often referred to as a COFFIN or BUNKER cases.
  • SDMT – Single Deck Meat
  • MDMT – Multi Deck Meat
  • MDDRY – Multi Deck Dairy
  • SVCDLI – Service deli
  • SVCFSH – Service Fish
  • SVCMT – Service Meat
  • RIFF – Reach In Frozen Food
  • RIIC – Reach in Ice Cream
  • MDDLI – Multi Deck Deli
  • OFC – Oil Failure Control
  • LPC – Low Pressure Control
  • HPC – High/Head Pressure Control
  • DPC – Dual Pressure Control
  • CONTROLLER – EMS unit usually in the compressor room where you see what is going on with the system.
  • ACCUMULATOR – Located on the SUCTION side of the compressor unit. Used to prevent liquid slugging of compressor in the event of massive liquid returning, and aid in oil returning to compressor.
  • LIQUID SLUGGING – When liquid comes back to the compressor and SLUGS it. It can cause severe internal damage, broken pistons, bearings to spin out, etc. Instead of pumping VAPOR the compressor tries to pump LIQUID.
  • FLOODING – Refers to liquid coming back through the suction line.
  • WASHOUT – When liquid floods a compressor it WASHES OUT the oil in the compressor.
  • MIGRATION – When refrigerant vapor travels to the compressor and condenses.
  • CFM – Condenser Fan Motor.
  • EFM – Evaporator Fan Motor.
  • DELTA T – Difference in Temperature/pressure
  • EMS – Energy Management System


  • DRIERIs referred to when talking about liquid line filters.
  • PRDWTRCKProduce Wet Rack
  • MDPRDMulti Deck Produce
  • GWIFGrocery Walk In Freezer
  • DRYCLRDairy Cooler
  • PRBXProduce Box
  • BOXRefers to walk in Freezer/Cooler of any kind.
  • LRALocked Rotor Amps. This is the initial inrush of amps when any electric motor first starts up.
  • RLARunning Load Amps, refers to once a motor is already running.
  • FLAFull Load Amps
  • CANISTERHolds LIQUID core driers or a suction filter in a CAN or HOUSING.
  • 8145-00115 VAC PARAGON time clock.
  • 8145-20208 VAC PARAGON time clock
  • T/CTime Clock
  • VACVolts AC
  • VDCVolts DC
  • PECKERHEADSlang term for an electrical motor housing where the wiring/electrical terminals are located.
  • DRAIN/DROP LEGThis is the liquid line coming OUT of the condenser to “drop” into the receiver.
  • MTPRPMeat Prep is the area where the meat is cut. Known as the meat cutting room or the butcher block.
  • LLSLiquid Line solenoid.
  • EEPRElectronic evaporator pressure regulator.
  • N/ONormally Open
  • N/CNormally Closed
  • CCommon
  • TWO STAGE RACKThis is where the LOW temp rack discharge line discharges into the MEDIUM temp rack, lowering the head pressure, thus lowering the discharge temperature.

NOTE: When shutting off a TWO STAGE rack first shutoff the FIRST STAGE (LOW TEMP), wait approximately 10 minutes, then shutoff the second stage/medium temp rack. When turning the racks back ON start up the second stage/medium temp rack FIRST, wait 10 minutes, then start up the first stage/low temp rack last. VERY IMPORTANT TO REMEMBER!

Follow these steps on your journey to becoming a Journeyman!

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